The present invention relates to device for injecting, infusing, administering, dispensing or delivering a substance, and to methods of making and using such devices. More particularly, the present invention relates to a needle safety module which can be attached to an injection device, e.g. an injection pen or so-called automatic injectors. A product or substance contained in the injection device, such as a liquid medicament, can be administered to a patient by or via the safety module. In some embodiments, the present invention relates to a mechanism designed to enable safe handling of a needle and, in some embodiments, to a code by or from which it is possible to tell whether a needle has been used.
Needle safety modules typically comprise a housing in which a needle is accommodated so that it is axially immobile. The housing can be attached to an injection device. The needle is surrounded by a needle guard before and after an injection so that the user of the safety module can not pierce himself with the needle. In addition to being painful, inadvertent piercing can lead to infections, such as HIV or hepatitis. For an injection, the needle guard is placed on the desired injection point and pushed back into an injection position by pressing the needle guard against the injection point, causing the needle to pierce the injection point. Once the needle has been pulled out, the needle guard is pushed back far enough over the needle to cover it, for example by a spring. In most instances, the needle is to be used only once.
U.S. Pat. No. 6,855,129 B2 discloses a needle safety module which is designed so that once the needle safety module has been used, a needle guard is prevented from moving axially. The mechanism has a locking sleeve which is initially guided by a housing as the needle guard is pushed back in the proximal (rearward) direction. Once the guided movement is complete, the locking sleeve is rotated by the needle guard as the needle guard continues to be pushed backward. This rotating movement continues as the needle guard is moved in the distal direction due to projections disposed on the housing and recesses in the proximal end of the needle guard until a projection of the locking sleeve locates in a lock element formed by the housing. As a result, the needle guard is prevented from moving any farther in the distal direction. The housing has an opening, through which the projection of the locking sleeve can be seen when the locking sleeve is engaged with the housing in a locked arrangement.